Date: Sun, 02 Jul 1995 15:23:15 PDT From: Voradesh Yenbut <yenbut@cs.washington.edu> To: hackers@freebsd.org Subject: One cause of 2.05R instability found Message-ID: <199507022223.PAA13599@vetch.cs.washington.edu>
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A few days ago, I committed a 90MHz pentium system running 2.05R to be
a news server. The system was not stable at all. It kept on crashing
within 2 hours with "Fatal trap 12: page fault while in kernel mode"
and fault code "supervisor read, page not present". The crash always
happened at the same instruction pointer, i.e., ncr_complete+195
(as reported by gdb; I don't have the hex number with me) in ncr.c.
In ncr.c, ncr_complte+195 is at the following if statement:
if (DEBUG_FLAGS & DEBUG_TINY)
printf ("CCB=%x STAT=%x/%x\n", (unsigned)cp & 0xfff,
cp->host_status,cp->scsi_status);
where DEBUG_FLAGS is ncr_debug declared in ncr.c as
static int ncr_debug = SCSI_DEBUG_FLAGS;
I commented out the if statement, rebuilt and installed the new
kernel. The system has been running fine with the new kernel for two
days (though I still keep my fingers crossed).
Looks like accessing ncr_debug in ncr_complete() routine sometimes causing the
fault somehow. My system configuration as printed by kernel is attached below.
---------
Voradesh Yenbut Phone: +1 206 685-0912
BOX 352350, U of Washington FAX: +1 206 543-2969
Seattle, WA 98195 Email: yenbut@cs.washington.edu
FreeBSD 2.0.5-RELEASE #1: Fri Jun 30 17:55:47 PDT 1995
root@:/usr/src/sys/compile/BEAVER
CPU: 85-MHz Pentium 735\90 or 815\100 (Pentium-class CPU)
Origin = "GenuineIntel" Id = 0x524 Stepping=4
Features=0x1bf<FPU,VME,PSE,MCE,CX8,APIC>
real memory = 66715648 (16288 pages)
avail memory = 63160320 (15420 pages)
Probing for devices on the ISA bus:
sc0 at 0x60-0x6f irq 1 on motherboard
sc0: VGA color <16 virtual consoles, flags=0x0>
ed0 at 0x300-0x31f irq 10 maddr 0xcc000 msize 16384 on isa
ed0: address 00:00:c0:0c:f8:75, type SMC8216/SMC8216C (16 bit)
sio0 at 0x3f8-0x3ff irq 4 on isa
sio0: type 16550A
sio1 at 0x2f8-0x2ff irq 3 on isa
sio1: type 16550A
sio2 at 0x3e8-0x3ef irq 5 on isa
sio2: type 16550A
sio3 at 0x2e8-0x2ef irq 7 on isa
sio3: type 16550A
fdc0 at 0x3f0-0x3f7 irq 6 drq 2 on isa
fdc0: NEC 72065B
fd0: 1.44MB 3.5in
npx0 on motherboard
npx0: INT 16 interface
Probing for devices on the pci0 bus:
configuration mode 2 allows 16 devices.
chip0 <Intel 82434LX PCI cache memory controller> rev 17 on pci0:0
chip1 <Intel 82378IB PCI-ISA bridge> rev 3 on pci0:2
ncr0 <ncr 53c815 scsi> rev 3 int a irq 9 on pci0:6
reg20: virtual=0xf5dfcc00 physical=0xffbffc00 size=0x100
ncr0: restart (scsi reset).
ncr0 scanning for targets 0..6 (V2 pl21 95/03/21)
ncr0 waiting for scsi devices to settle
(ncr0:0:0): "SEAGATE ST31200N 8648" type 0 fixed SCSI 2
sd0(ncr0:0:0): Direct-Access
sd0(ncr0:0:0): FAST SCSI-2 100ns (10 Mb/sec) offset 8.
1006MB (2061108 512 byte sectors)
(ncr0:1:0): "SEAGATE ST31200N 8648" type 0 fixed SCSI 2
sd1(ncr0:1:0): Direct-Access
sd1(ncr0:1:0): FAST SCSI-2 100ns (10 Mb/sec) offset 8.
1006MB (2061108 512 byte sectors)
(ncr0:2:0): "SEAGATE ST31200N 8648" type 0 fixed SCSI 2
sd2(ncr0:2:0): Direct-Access
sd2(ncr0:2:0): FAST SCSI-2 100ns (10 Mb/sec) offset 8.
1006MB (2061108 512 byte sectors)
vga0 <VGA-compatible display device> rev 0 int a irq 9 on pci0:14
pci0: uses 16640 bytes of memory from a0000000 upto ffbffcff.
pci0: uses 256 bytes of I/O space from fc00 upto fcff.
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